The move to a unified platform is by far the most significant change customers will experience since the merger of United and Continental to form the world's largest airline, known as United Airlines and owned by United Continental Holdings Inc (UAL.N).

"This, from the customer perspective, is probably the biggest thing that they will see," Martin Hand, United's senior vice president of customer experience, said on Wednesday.

"This truly brings the two carriers together from the customer side," he said.

Hand said United Airlines has adopted the reservation platform of the former Continental Airlines and has spent months training about 15,000 employees -- including reservations agents -- on the software.

United has already moved millions of passenger records to the Continental platform and has notified its frequent flyers of the upcoming change.

"That will come to a culmination overnight Friday night to Saturday morning," Hand said.

Early Saturday morning, the Continental.com website will disappear in favour of the United branded site.

Hand said the company chose the Continental platform over United partly because it offered more flexibility to users making reservations on the site.

He declined to disclose the cost of migrating to the single platform.

United and Continental closed their $3.17 billion merger more than a year ago. Former Continental Chief Executive Jeff Smisek leads the combined carrier.

The new United Continental spent much of 2011 rebranding itself and combining some of its customer service functions to slowly erase the line separating the two airlines. The company won government approval last year to operate as a single carrier.

United Continental has painted most of the old Continental planes in the United livery and is finishing the rest.

Out of public view, however, United Continental faces the tall order of blending its separate unionized work forces and achieving joint labour contracts.

Migration to a single reservation system comes with risk, as US Airways Group (LCC.N) learned in 2007 when it attempted to combine the reservation systems of the former America West Airlines and US Airways. The two airlines merged in 2005.

A glitch in their combined system caused the self-service kiosks to fail, forcing passengers to stand in extraordinarily long lines and check in with ticket agents. Thousands of travellers waited in the lines and about 500 travellers at the Charlotte, North Carolina, hub missed their flights.

Hand said United consulted US Airways, its partner in the global Star Alliance, about the pitfalls of moving to a single reservation system.

Delta Air Lines (DAL.N) had a much smoother transition to a single reservation system following its 2008 merger with Northwest Airlines.

"Whenever you combine different technology there's risk," said Ray Neidl, an aerospace analyst at Maxim Group.

"In the case of United, they have done a lot of planning. But you never can tell," he said. "At the last minute, there's always likely to be some bugs that pop up."

(Reporting By Kyle Peterson; editing by John Wallace)

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